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Biomedical subjects

J Belin

Publications and source records attributed to J Belin.

At least 19 recordsLinked to original sources
PubMed1989

Effects of dietary linoleic acid and gamma linolenic acid on platelets of patients with multiple sclerosis.

The effects of dietary evening primrose oil (rich in linoleic acid and gamma-linolenic acid) were studied on platelets of multiple sclerosis (MS) patients and controls. It was found that platelet aggregation (ADP, thrombin and collagen), platelet fibrinogen binding and platelet glycoprotein (sialic acid and N-acetyl glucosamine) content were not significantly modified by evening primrose oil in MS patients and controls. Moreover, platelet fibrinogen binding and platelet glycoprotein (sialic acid and N-acetyl glucosamine) content were determined for the first time in MS patients and found similar to controls. Platelets of MS patients aggregated more to thrombin and collagen compared to controls, but the difference was only significant with thrombin aggregation after the oil treatment. This study does not show a significant effect of evening primrose oil on platelets of MS patients.

8,11,14-Eicosatrienoic Acid↗
PubMed1986

The effects of dietary (n-3) fatty acid supplementation on lipid dynamics and composition in rat lymphocytes and liver microsomes.

Rats were fed diets devoid of (n-3) fatty acids (olive oil supplementation) or high in (n-3) fatty acids (fish oil supplementation) for a period of 10 days. In spleen lymphocytes and liver microsomes derived from animals fed fish oil diets, relatively high levels of (n-3) eicosapentaenoic (20:5), docosapentaenoic (22:5) and docosahexaenoic acids (22:6) were obtained compared to minimal levels when fed the olive oil diet. When the average lipid motional properties were examined by measuring the fluorescence anisotropy of diphenylhexatriene, no significant different was found between intact liver microsomes from animals fed the two diets. However, when lipid motion was examined in vesicles of phosphatidylcholine, isolated from the microsomes from fish oil fed animals (21.4% (n-3) fatty acids), the fluorescence anisotropy was significantly less than the corresponding phosphatidylcholine from olive oil fed animals (5.6% (n-3) fatty acids), indicating a more disordered or fluid bilayer in the presence of higher levels of (n-3) fatty acids. Phosphatidylethanolamine (n-3) fatty acids were also elevated after fish oil supplementation (41.3% of total fatty acids), compared to the level after olive oil supplementation (21.4%). The major effect of the fish oil supplementation was a replacement of (n-6) arachidonic acid by the (n-3) fatty acids and when this was 'modeled', using liposomes of synthetic lipids, 1-palmitoyl-2-arachidonyl(n-6) or docosahexaenoyl(n-3)-phosphatidylcholine, significant differences in lipid motional properties were found, with the docosahexaenoate conferring a more disordered or fluid lipid environment. Thus it appears that although lipid order/fluidity can be significantly decreased by increases in the highly unsaturated (n-3) fatty acid levels, alterations in membrane domain organization and/or phospholipid molecular species composition effectively compensated for the changes, at least as far as average lipid motional properties in the intact membranes was concerned.

Animals↗
PubMed1986

Influence of dietary lipids on the effect of chlorpromazine on membrane properties of rabbit red cells.

The effect of diets containing different types of common natural oils on physical properties of red cells was investigated by using rabbits. The rabbits were fed for 18 months on a standard diet in which 8% of its energy content was provided by safflower oil and 32% energy by either more safflower oil or fish oil, linseed oil, olive oil or palm oil. Erythrocyte deformability was significantly decreased by the fish oil diet compared with each of the other diets. Osmotic fragility was significantly less (66 mM) for red cells from rabbits fed on the linseed oil diet, and significantly greater (71 mM) for red cells from rabbits on the fish oil diet, than for red cells from rabbits on the other three diets which did not differ significantly from each other (68 mM). With rabbits on the standard diet, the resistance of their erythrocytes to osmotic haemolysis was increased by chlorpromazine at concentrations below and decreased by concentrations above 30 microM. The dietary oils caused significant changes in the effects of chlorpromazine on osmotic fragility. The concentration at which the effect of chlorpromazine reversed from antihaemolytic to prohaemolytic was decreased by the safflower and linseed oil diets and increased by the fish oil diet, compared with the olive and palm oil diets. Analysis of the fatty acid compositions of the dietary oils on the one hand and of the red cell phospholipids on the other established, specifically, that in the presence of 30 microM chlorpromazine the percentage haemolysis was directly proportional to the linoleate content of the red cell phospholipids.

Animals↗
PubMed1986

The influence of graded hyperglycemia with and without physiological hyperinsulinemia on forearm glucose uptake and other metabolic responses in man.

We studied the influence of hyperglycemia on glucose homeostasis in man by determining the effect of graded hyperglycemia on peripheral glucose uptake and systemic metabolism in the presence of basal and increased serum insulin concentrations in 10 normal men. This was achieved by the simultaneous application of forearm and clamp techniques (euglycemic and hyperglycemic) during the combined iv infusion of somatostatin, glucagon, and insulin. While mean (+/- SE) basal serum insulin levels (14 +/- 2 microU/ml) were maintained, the elevation of fasting arterial glucose concentrations (90 +/- 1 mg/dl) to 146 +/- 1 and 202 +/- 1 mg/dl (each for 120 min) increased forearm glucose uptake (FGU) only modestly from 0.06 +/- 0.01 to 0.15 +/- 0.02 and then to 0.24 +/- 0.03 mg/100 ml forearm X min, respectively. During physiological hyperinsulinemia (47 +/- 3 microU/ml), the influence of similar graded hyperglycemia on FGU was considerably enhanced. At plasma glucose concentrations of 90 +/- 1, 139 +/- 1, and 206 +/- 1 mg/dl, FGU rose to 0.33 +/- 0.05, 0.59 +/- 0.07, and 0.83 +/- 0.12 mg/100 ml forearm X min, respectively. The glucose infusion rate required to maintain the glucose clamp with basal insulin levels was 1.08 +/- 0.20 and 2.67 +/- 0.39 mg/kg X min at glucose concentrations of 146 +/- 1 and 202 +/- 1 mg/dl, respectively. During physiological hyperinsulinemia, however, the glucose infusion rate required was 4.15 +/- 0.39, 9.45 +/- 1.05, and 12.70 +/- 0.81 mg/kg X min at glucose levels of 90 +/- 1, 139 +/- 1, and 206 +/- 1 mg/dl, respectively. Lactate concentrations rose significantly during hyperglycemia, but the rise in the presence of increased insulin concentrations (from 0.72 +/- 0.06 to 1.31 +/- 0.11 mmol/liter; P less than 0.001) considerably exceeded the increment (from 0.74 +/- 0.05 to 0.92 +/- 0.03 mmol/liter) with basal insulin levels. While both FFA and glycerol concentrations were immediately reduced by euglycemic hyperinsulinemia, the fall in FFA during hyperglycemia in the presence of basal insulin levels preceded the decrease in glycerol concentrations by 45 min. Forearm oxygen consumption did not change throughout the study.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1985

Response to platelet-activating factor of platelets from patients with multiple sclerosis.

The response of Multiple Sclerosis (MS) and control platelets to different concentrations of platelet-activating factor was studied. At concentrations in the range 10(-7) to 10(-5)M, it was found that the MS platelets tended to aggregate fully at lower concentrations than was the case with control platelets. At a concentration of 10(-6)M, it was found that in 19 cases the MS platelets gave a full aggregation response whilst 4 cases showed biphasic but full aggregation, whereas at this concentration the control platelets showed full aggregation in only 2 cases, biphasic but less complete aggregation in 5 cases and reversible aggregation in 16 cases. In crossover studies, it could be shown that MS platelets resuspended in control platelet-poor plasma still showed enhanced aggregability and that the response of control platelets was unaffected by resuspension in MS platelet-poor plasma. Differences were also seen in susceptibility of platelets of MS and control subjects to inhibition by indomethacin, bromophenacyl bromide (a phospholipase inhibitor) and verapamil (a Ca2+ antagonist). It is suggested that the hyperaggregability of the MS platelets could reside in the platelets themselves, and may be associated with enhanced phospholipase activity.

Acetophenones↗
PubMed1979

Inhibition of complement-dependent rosette formation after lymphocyte incubation with fatty acids.

Overnight incubation of lymphocytes with certain fatty acids bound to albumin has previously been shown to modify the fatty acid composition of cellular phosphoglycerides without impairing viability, and also to inhibit mitogen and antigen-induced lymphocyte transformation. In the present study, incubation of human lymphocytes with palmitic acid or with linoleic acid impaired their capacity to form complement-dependent rosettes but had no effect on either spontaneous rosette formation with sheep erythrocytes or Fc(gamma)-dependent rosette formation. With mouse lymphocytes, complement-dependent rosette formation was suppressed only following incubation with linoleic acid and there was no effect on Fc(gamma)-dependent rosette formation. Although the mechanism of these effects remains to be elucidated the results suggest that control of membrane lipid composition may modify the important in vivo immunological functions which involve complement receptors.

Animals↗
PubMed1977

Phytohaemagglutinin stimulation of human lymphocytes: effect of fatty acids on uridine uptake and phosphoglyceride fatty acid profile.

1. When added to cultures of human peripheral lymphocytes, saturated (palmitate, stearate, heptadecanoate) and unsaturated (oleate, linoleate, arachidonate) fatty acids bound to albumin at an acid-albumin ratio of 2:1, inhibited the phytohaemaegglutinin-stimulated uptake of [14C]-uridine. Uridine uptake in unstimulated cells was not affected by any of these fatty acids. 2. When saturated and unsaturated acids were present simultaneously in the incubation mixture the inhibit but relieved the inhibitory effects of both saturated and unsaturated fatty acids. 4. Stimulated and unstimulated cells incorporated exogenous fatty acids into membrane phosphoglycerides. Details of the fatty acid profiles are given. 5. Evidence is presented that the inhibition results, at least in part, from modification of phosphoglyceride fatty acid profile.

Dose-Response Relationship, Drug↗